In the field of fiber optic signal transmission, proper centering of the optical fiber in the connector is critical to avoid what is called "insertion losses", i.e., losses in the transmission of light waves through the connector. Most often, an optical fiber is terminated within a cylindrical ferrule fabricated of such materials as ceramic. Known processes allow the fiber to be generally centered in a bore of the ferrule. The ferrule then is positioned within the fiber optic connector by various connector bodies, plugs or the like.
However, problems are caused because the core of the optical fiber is not centered within the ferrule. This creates "insertion losses". The core can be misaligned for various reasons. First, the core may not be centered with respect to the outside diameter of the fiber. Second, the hole in the ferrule which receives the fiber may not be centered with respect to the outside diameter of the ferrule. Third, the hole in the ferrule is bigger than the fiber and the fiber may be offset in the hole. Other considerations include the fact that the fiber may not even be round.
The present invention is directed to solving the problems discussed above by a fiber optic connector assembly which includes two parts, namely a connector body and an inner plug and wherein the inner plug can be rotationally adjusted relative to the connector body after assembly of the body in an outer member, with the adjustment being carried out from the front of the connector after it has been assembled. This procedure effectively "tunes" the connector by rotationally adjusting the plug so that the fiber core offset is towards a predetermined reference, usually the connector key. Optimum fiber alignment (or lowest insertion loss) is achieved at the interface of two such tuned connectors.